Tough call, I think it's really a semantic thing. I checked the glossary after seeing your post and it didn't clear it up, could go either way.

If Eric and I never slept together again I would have lost a connection with a lover who I care about, so that would be lame as heck, but I wouldn't be losing a relationship, it'd be no tragedy -- we'd still just be close friends. And there's no romance there to begin with. Whereas with Gia, if we never regained the physical/romantic aspect of our relationship and became just friends I would feel a great sense of loss. So, while our times together have largely been three-person times, if we're a triangle-shape we're not at all an equilateral one.

To me, the vee-ness of the situation feels very clear because I feel the "line" of the relationship attaching me at the wing to Gia at the hinge, and I see the line between Gia and Eric burning brightly, whereas there's not a corresponding "line" attaching me and Eric that would close the shape and make it a triangle/triad. The feeling of vee-ness was all the stronger for me when I was letting my unrequited feelings for Eric bum me out, because the absence of that line was what was making me sad (lately I've felt that much less keenly, I think I'm getting over wanting something I don't have with him).

I think to me it comes down to one thing. Are Eric and I bf and gf? No? Then no triad, all appearances to the contrary notwithstanding. I find the distinction important when dealing with friends, because it's uncomfortable to have people assume things that are wrong about your relationship with someone, and it's very easy for people to assume I'm dating both of them. Which, again, when I was more focused on pining, just made me sad.